The different types of aquatic vegetation growth controlled by the present invention can be divided into two groups: submersed and emergent. Submersed aquatic vegetation is attached to the hydrosoil by roots. Generally, submersed aquatic vegetation grows in water depths between 0.5 and 2.5 meters. Emergent varieties depend on the water body for existence but grow primarily in shallow water or on the shoreline and are not able to grow in deep water.
Traditional mechanical methods available for aquatic plant control have been largely limited to two technological types: dredging and harvesting.
DREDGING:
Dredging was designed for deepening and widening water channels for water navigation and for creating canals and ditches for the passage of water. Attempts at using dredging for the control and removal of submersed aquatic vegetation was limited to shoreline areas where the dredger could reach and where the shoreline topography allowed the dredger access. The process did achieve limited success removing emergent aquatic vegetation, where access to the water edge, allowed a dredger to be mobilized to and along without obstructions barring its path for example on the groomed banks of a canal.
HARVESTINGS:
Harvesting has long been known as the most environmentally acceptable and most cost-effective method for control of aquatic vegetation. The procedure is accomplished using a self propelled harvester vessel equipped with an adjustable harvesting head attached to the front of the harvester which can be raised or lowered into the water. The bottom of the harvester head is equipped with a reciprocating sickle bar cutter which cuts the aquatic vegetation approximately 8 cm above the soil surface, up to a maximum water depth of 1.8 meters. The cut vegetation falls onto a conveyor which conveys the vegetation to the surface of the water and into a storage compartment of the harvester. When the storage compartment is full the harvester propels itself to shore where it hooks up to and conveys the harvested aquatic vegetation into a disposal trailer. Although regrowth of submersed aquatic vegetation is reduced in most cases, regrowth normally occurs every year after treatment. Because of annual regrowth, efforts have been made to design equipment that would remove the roots of aquatic vegetation rather than or in combination with harvesting to yield better and longer lasting control results.
The objectives of the present invention are to obtain a more productive and cost-effective method of de-rooting, than currently available. The process is intended to provide relief from regrowth as long as or longer than that achieved by other de-rooting equipment. The most notable technologies used prior to the present invention were the spring shanked cultivator and the rototiller.
CULTIVATOR:
One of the first aquatic implements used on a sizable scale for de-rooting nuisance aquatic vegetation was a terrestrial cultivator. It was pulled along shallow shoreline areas by a specially adapted muskeg tractor. The cultivator consisted of three rows of offset shanks each with a shovel or sweep attached to the bottom of the shank. The shanks were staggered in the rows to ensure complete overlap within the operating width. The cultivator shovels were set to penetrate 10 to 15 cm into the substrate. As they sliced below the root crown of the plant, they uprooted the plant and caused sufficient agitation to shake off the soil particles, allowing the root crown to float.
The terrestrial cultivator proved to be very unsafe because the uneven contour of lake bottoms caused tipping and sinking of the equipment. The process was slow and the equipment was limited to operating in a maximum water depth of 1.25 meters.
ROTOTILLER:
The rototiller was the next machine developed and is still used today in de-rooting operations. The rototiller head is equipped with L-shaped blades fixed to a hydraulically driven rotating shaft. The blades are very similar to those used on a conventional garden rototiller. The head is supported by two arms which are mounted on opposite sides of a paddlewheel-driven barge. These support arms pivot just behind the center of the barge and are raised and lowered by a cable winch mounted on the barge deck.
The rototiller process is slow and is limited in its usefulness by poor maneuverability. There is little or no positive guidance or tracking ability through stands of vegetation. It is used primarily in deep water between 2 and 4.5 meters. The design of the head makes it susceptible to damage by under water obstacles. Driving the L-shaped blades through the soil takes a considerable amount of power, resulting in low production.
With existing technology no one machine can remove and control aquatic vegetation in both shallow and deep water conditions. Nor is there a prior art machine available that can de-root both submersed and emergent aquatic vegetation. The low de-rooting productivity of available technologies also mean that existing de-rooting equipment is expensive to operate.
De-rooting with previously designed equipment creates large problems after a treatment is performed because of the floating debris left behind. It is necessary to bring in harvesters to skim up the floating debris in order to prevent it from reestablishing itself or from drifting to neighbouring sites and infecting areas which were not previously infected with vegetative growth. This necessitates either the use of two machines or de-rooting aquatic vegetation in the early spring or late fall when there are only roots to remove.
It is therefore desired to provide new or improved de-rooting apparatus that ameliorates problems with the prior art.